The invention relates to a motor vehicle audio system comprising an audio signal receiver, at least one amplifier connected thereto by way of an optical waveguide, and a loudspeaker.
A system of this type is known from European Patent Document EP 0 027 043 B (corresponding U.S. Pat. No. 4,282,605). Such an audio system is operated by means of an operating voltage which is equal to the normal onboard power supply voltage of preferably 12 volt. In the case of loudspeakers with a resistance of 8Ω, particularly in the case of powerful amplifiers, a distortion factor occurs which is also clearly noticeable acoustically and which impairs the listening enjoyment. If, on the other hand, a higher operating voltage is to be used for the amplifiers in order to avoid the harmonic distortion, the interferences, which necessarily occur in the onboard power supply and which also occur on the supply lines of the amplifiers, result in clearly audible clicks and plops.
It is an object of the invention to provide an audio system of the initially mentioned type which permits an undisturbed listening enjoyment.
The invention achieves this object by providing an audio system of the type referred to above, wherein a separate amplifier is supplied with a significantly higher operating voltage than the at least one amplifier for other audio frequencies.
The invention provides a separation of the audio signals of the bass range and a separate amplification therefor. The high operating voltage is used only for supplying the separate amplifier. In addition, the use of two independent amplifiers can also be provided for the medium/high frequency range.
The amplifier of the bass range receives a supply voltage of preferably 42 volt, while the medium/high frequency range is supplied with, for example, 12 volt.
Occurring electric interferences do not affect the bass range because they have significantly higher frequencies. The use of a supply voltage of 42 V therefore results in a high power yield in the low-bass range while simultaneously acoustic interferences cannot be perceived. In contrast, such a high power yield is not required for the medium/high frequency range. The use of amplifiers with 12V permits a sufficient power yield. The power required for the medium/high frequency range can and will clearly be lower than for the bass range.
The invention will be further explained by means of the drawing.